Method and device for controlling a lifting load

Abstract

A control method implemented in a variable speed drive for controlling a lifting load, the load control being carried out according to a first control profile that includes the following: accelerating the load with a view to reaching a first speed, decelerating the load upon receiving a deceleration order, and stopping the load. When the load receives a deceleration order when it is at a current speed lower than the first speed, the method determines a second speed lower than the first speed and higher than the current speed, the second speed having an optimal value for minimizing the load running time until stopping.

The invention claimed is: 
     
       1. A method of control implemented in a variable speed drive for controlling a lifting load, the control of the load being carried out according to a first control profile which comprises:
 acceleration of the load with a view to reaching a first speed in accordance with a first non-linear acceleration ramp; 
 deceleration of the load subsequent to receipt of a deceleration order; and 
 stopping of the load; 
 wherein when the load receives the deceleration order while it is at a current speed below the first speed, the method further comprises: 
 determining a second speed below the first speed and above the current speed, the second speed having an optimal value so as to minimize a travel time of the load until stopping; and 
 generating and applying a second control profile replacing the first control profile and comprising accelerating the load until reaching the second speed according to a second non-linear acceleration ramp taking account a remaining distance to be traveled, followed by a deceleration and by a stopping. 
 
     
     
       2. The method as claimed in  claim 1 , wherein the second control profile comprises maintaining the speed of the load at the second speed for a determined duration. 
     
     
       3. The method as claimed in  claim 1 , wherein, between the deceleration and the stopping, the second control profile comprises maintaining the speed of the load at a third speed below the second speed. 
     
     
       4. The method as claimed in  claim 1 , wherein, on completion of the deceleration, the second control profile comprises receiving a stopping order. 
     
     
       5. The method as claimed in  claim 4 , wherein after receipt of the stopping order, the second control profile comprises deceleration until stopping. 
     
     
       6. The method as claimed in  claim 4 , wherein the deceleration order or the stopping order is dispatched by a sensor in front of which the lifting load passes. 
     
     
       7. The method as claimed in  claim 4 , wherein the deceleration order or the stopping order is dispatched by an automaton connected to the variable speed drive. 
     
     
       8. A variable speed drive for controlling a lifting load, a control of the load being carried out according to a first control profile which comprises:
 acceleration of the load with a view to reaching a first speed in accordance with a first non-linear acceleration ramp; 
 receipt of a deceleration order; 
 deceleration of the load; and 
 stopping of the load; 
 wherein when the load receives the deceleration order at a current speed below the first speed, the variable speed drive implements: 
 means for determining a second speed below the first speed and above the current speed, the second speed having an optimal value so as to minimize a travel time of the load until stopping; and 
 means for generating and implementing a second control profile replacing the first control profile and comprising accelerating the load until reaching the second speed according to a second non-linear acceleration ramp taking account a remaining distance to be traveled, followed by a deceleration and by a stopping. 
 
     
     
       9. The variable drive as claimed in  claim 8 , further comprising means for maintaining the speed of the load at the second speed for a determined duration. 
     
     
       10. The variable drive as claimed in  claim 8 , wherein the variable speed drive comprises means for maintaining the speed of the load at a third speed below the second speed. 
     
     
       11. The variable drive as claimed in  claim 8 , wherein the second control profile comprises a receipt of a stopping order. 
     
     
       12. The variable drive as claimed in  claim 11 , wherein the second control profile comprises a deceleration until stopping subsequent to the receipt of the stopping order. 
     
     
       13. The variable drive as claimed in  claim 11 , connected to an external sensor configured to dispatch the deceleration order or the stopping order when it detects passage of the lifting load. 
     
     
       14. The variable drive as claimed in  claim 11 , connected to an automaton configured to dispatch the deceleration order or the stopping order.